Asymmetric Epoxidation Of Dihydronaphthalene With A Synthesized Jacobsens

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Term Paper Title	Asymmetric Epoxidation Of Dihydronaphthalene With A Synthesized Jacobsens
# of Words	2423
# of Pages (250 words per page double spaced)	9.69

Asymmetric Epoxidation of Dihydronaphthalene with a Synthesized Jacobsen's
Catalyst

Asymmetric Epoxidation of Dihydronaphthalene with a Synthesized Jacobsen's
Catalyst

Justin Lindsey
12/08/96
Chem 250 GG
Professor
Tim Hoyt
TA: Andrea Egans

Abstract.   1,2 diaminocyclohexane was reacted with L-(+)-tartaric acid to yield
(R,R)-1,2-diaminocyclohexane mono-(+)-tartrate salt. The tartrate salt was then
reacted with potassium carbonate and 3,5-di-tert-butylsalicylaldehyde to yield
(R,R)-N,N'-Bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine, which was
then reacted with Mn(OAc)2*4H2O and LiCl to form Jacobsen's catalyst.  The
synthesized Jacobsen's catalyst was used to catalyze the epoxidation of
dihydronaphthalene.  The products of this reaction were isolated, and it was
found that the product yielded  1,2-epoxydihydronaphthalene as well as
naphthalene.

Introduction

     In 1990, professor E.N. Jacobsen reported that chiral manganese
complexes had the ability to catalyze the asymmetric epoxidation of
unfunctionalized alkenes, providing enantiomeric excesses that regularly
reaching 90% and sometimes exceeding 98% .  The chiral manganese complex
Jacobsen utilized was [(R,R)-N,N'-Bis(3,5-di-tert-butylsalicylidene)-1,2-
cyclohexanediaminato-(2-)]-manganese (III) chloride (Jacobsen's Catalyst).

(R,R) Jacobsen's Catalyst Jacobsen's catalyst opens up short pathways to
enantiomerically pure pharmacological and industrial  products via the
synthetically  versatile epoxy function .
     In this paper, a synthesis of Jacobsen's catalyst is performed (Scheme
1).  The synthesized catalyst is then reacted with an unfunctional alkene
(dihydronaphthalene) to form an epoxide that is highly enantiomerically enriched,
as well as an oxidized byproduct.
     Jacobsen's work is important because it presents both a reagent and a
method to  selectively guide an enantiomeric catalytic reaction of industrial
and pharmacological importance.   Very few reagents, let alone methods, are
known to be able to perform such a function, which indicates the truly
groundbreaking importance of Jacobsen's work.

Experimental Section

     General Protocol.    99% L-(+)- Tartaric Acid, ethanol,
dihydronaphthalene and glacial acetic acid were obtained from the Aldrich
Chemical Company. 1,2 diaminocyclohexane (98% mix of cis/trans isomers) and
heptane were obtained from the Acros Chemical Company.  Dichloromethane and
potassium carbonate were obtained from the EM Science division of  EM Industries,
Inc.  ...

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